1. Field of the Invention
The present invention relates generally to the field of agricultural chemical applicators, and more particularly, is directed to a hand-held spot applicator including means to precisely adjust the flow rate of application.
2. Discussion of the Prior Art
Mechanisms to aid in the application of liquid agricultural chemicals to gardens, fields and other surface areas have long been a popular subject matter for prior workers in the art. Numerous types of mechanical applicators and sprayers have been developed to spread agricultural chemical products such as fertilizers, insecticides, pesticides, herbicides and the like and these prior art devices have been both manually and mechanically operated. More recently, the apparatus and equipment designed for vehicular transport has tended to become quite complicated in nature and expensive in manufacture and operation. Such types of spray apparatus have been designed for direct attachment to various types of vehicles including both ground vehicles and aircraft and such prior art equipment has generally proven to be effective in substantially uniformly applying the desired chemicals.
Agricultural chemical application equipment has also been particularly designed for manual use by an individual and it is in this particular area that the present invention finds special utility. In U.S. Pat. No. 3,648,935 by the inventor of the present application, a spray apparatus with a rotary movable head has been disclosed. In this apparatus, a movable rotary spray head is rotatively powered through associated apparatus including ground contacting wheels so that as the device is moved over the ground surface, the wheels generate rotary forces sufficient to rotate the rotary spray head. In other applications, the rotary spray head has been removed from the ground contacting wheels and has instead been equipped with a small electric motor for rotatively powering the spray head. By equipping the small motor with a suitable battery, a worker equipped with a suitable liquid storage tank can walk over the ground surface to be sprayed and the electric motor will provide the rotary energy necessary to turn the spray head for agricultural chemical application purposes.
In U.S. Pat. No. 2,162,057, a knapsack type of spraying apparatus has been disclosed wherein a worker can carry the liquid materials to be sprayed in a tank carried on his back. A hose interconnects the liquid contents stored within the tank with a rigid tube and nozzle through a control valve whereby the operator can apply the liquids directly upon the areas to be sprayed as he walks.
While the prior art applicators which are known to the applicant have generally been effective in applying the agricultural liquid chemicals directly upon selected target areas, so far as is known, the prior art devices require an integral pump or require that the tank be pressurized in order to generate sufficient forces for spray application purposes. Further the prior devices are rather randomly controlled and there is no known means to effectively apply a precisely controlled quantity of chemical product directly upon the target area. Under the circumstances, in view of the lack of precision capability of the presently available equipment, it has been found that some areas will receive more than the desired chemical treatment while others will receive less. Thus, the need remains to provide a readily controllable applicator that is capable of applying precise quantities of liquid chemicals in a continuous and reliable manner.